Intra-coronary Imaging for the Evaluation of Plaque Modifications Induced by Drug Therapies for Secondary Prevention

PURPOSE OF REVIEW

Patients diagnosed with coronary artery disease are at a high risk of subsequent cardiovascular events; therefore, secondary prevention in the form of therapeutic lifestyle changes, and drug therapies is vital. This article aims to review potential application of intra-coronary imaging for the evaluation of plaque modifications, induced by medications for secondary prevention for CAD.

RECENT FINDINGS

Intra-coronary imaging provides detailed information on the atherosclerotic plaque which is the primary pathological substrate for the recurrent ischemic cardiovascular events. These modalities can detect features associated with high risk and allow serial in vivo imaging of lesions. Therefore, intravascular imaging tools have been used in landmark studies and played a role in improving our understanding of the disease processes. Changes in size and plaque composition over time can be evaluated by these tools and may help understanding the impact of a treatment. Moreover, surrogate imaging end points can be used when testing new drugs for secondary prevention.

Assessment of the Role of Carotid Atherosclerosis in the Association Between Major Cardiovascular Risk Factors and Ischemic Stroke Subtypes

IMPORTANCE

A better understanding of the role of atherosclerosis in the development of ischemic stroke subtypes could help to improve strategies for prevention of stroke worldwide.

OBJECTIVE

To assess the role of carotid atherosclerosis in the association between major cardiovascular risk factors and ischemic stroke subtypes.

DESIGN, SETTING, AND PARTICIPANTS

The prospective China Kadoorie Biobank cohort study was conducted in the general population of 5 urban and 5 rural areas in China, with a baseline survey obtained between June 2004 and July 2008. A random sample of 23 973 participants with no history of cardiovascular disease at enrollment who had carotid artery ultrasonographic measurements recorded at a resurvey from September 2013 to June 2014 were included. Data analysis was performed from July 1, 2016, to April 10, 2019.

EXPOSURES

Major cardiovascular risk factors (ie, blood pressure [BP], blood lipid levels, smoking, and diabetes).

MAIN OUTCOMES AND MEASURES

Carotid ultrasonographic measures of plaque burden (derived from number and maximum size of carotid artery plaques at resurvey) and first ischemic stroke during follow-up (n = 952), with subtyping (data release, August 2018) as lacunar (n = 263), probable large artery (n = 193), probable cardioembolic (n = 66), or unconfirmed (n = 430). Associations between cardiovascular risk factors, carotid plaque burden, and ischemic stroke subtypes were adjusted for age, sex, and geographic area.

RESULTS

The 23 973 participants in the study had a mean (SD) age of 50.6 (10.0) years, and 14 833 (61.9%) were women. Systolic BP had a stronger association (odds ratio [OR] per SD, 1.51; 95% CI, 1.42-1.61) than plaque burden (OR per SD, 1.34; 95% CI, 1.26-1.44) with ischemic stroke, and the associations of systolic BP with each subtype of ischemic stroke were modestly attenuated by adjustment for plaque burden. After adjustment for BP, plaque burden had a stronger association with probable large artery stroke (OR, 1.43; 95% CI, 1.24-1.63) than with lacunar stroke (OR, 1.25; 95% CI, 1.10-1.43) but was not associated with probable cardioembolic stroke (OR, 1.06; 95% CI, 0.83-1.36).

CONCLUSIONS AND RELEVANCE

Although BP was an important risk factor for all ischemic stroke subtypes, carotid atherosclerosis was an important risk factor only for large artery and lacunar strokes, suggesting that drug treatments targeting atherosclerosis may reduce the risk of stroke subtypes to different extents.

The role of 64/128-slice multidetector computed tomography to assess the progression of coronary atherosclerosis

OBJECTIVES

We studied the progression of coronary atherosclerosis over time as detected by multidetector computed tomography (MDCT) in relation to risk factors and plaque composition.

BACKGROUND

Studies using MDCT are limited to the assessment of the degree of stenosis without taking into consideration the plaque composition that is seen by MDCT.

METHODS

This study included 200 patients, complaining of chest pain and referred to do 64/128-contrast-enhanced MDCT for the second time, and both studies were retrieved and evaluated for the presence of plaque, plaque type, vessel wall remodeling, percent area, and diameter stenosis and compared in both studies. Plaque progression over time and its association with risk factors were determined.

RESULTS

We included 200 patients, and 348 plaques were detected by 64/128 MDCT. The duration between follow-up and baseline studies was 25.9 ± 19.2 month. In all, 200 plaques showed progression (57.47%), 122 were stable (35.06%), and 26 regressed (7.47%). In longitudinal regression analysis, the presence of history of diabetes mellitus and dyslipidemia and the absence of intraplaque calcium deposits were independently associated with plaque progression over time (P < 0.0001).

CONCLUSION

Coronary plaque burden of patients with chest pain and no history of acute coronary syndrome significantly increased over time. Progression is dependent on plaque composition and cardiovascular risk factors. Larger studies and longer follow-up period are needed to confirm the determinant factors for plaque progression.

Delineation of atherosclerotic plaque using subharmonic imaging filtering techniques and a commercial intravascular ultrasound system

The ability to delineate atherosclerotic plaque from the surrounding tissue using custom-developed subharmonic imaging (SHI) digital filtering techniques was investigated in vivo using a commercially available system. Atherosclerosis was induced in the aorta of two Watanabe Heritable Hyperlipidemic rabbits following which injections of an ultrasound contrast agent (UCA) Definity (Lantheus Medical Imaging, N Billerica, Massachusetts) were administered. Imaging was performed using a Galaxy intravascular ultrasound (IVUS) scanner (Boston Scientific, Natick, Massachusetts) equipped with an Atlantis® SR Pro Imaging Catheter (Boston Scientific). Four preliminary band-pass filters were designed to isolate the subharmonic signal (from surrounding tissue) and applied to the radio-frequency (RF) data. Preliminary filter performances were compared in terms of vessel-tissue contrast-to-tissue ratio (CTR) and visual examination. Based on preliminary results, a subharmonic adaptive filter and a stopband (SB) filter were designed and applied to the RF data. Images were classified as fundamental, SHI, and SB. Four readers performed qualitative analysis of 168 randomly selected images (across all three imaging modes). The images were scored for overall image quality, image noise, plaque visualization, and vessel lumen visualization. A Wilcoxon signed-rank test was used to compare the scores followed by intraclass correlation (ICC) evaluation. Quantitative analysis was performed by calculating the CTRs for the vessel-to-plaque and vessel-to-tissue (compared using a paired student's t test). Qualitative analysis showed SHI and SB to have significantly less image noise relative to the fundamental mode (p < 0.001). Fundamental mode scored significantly higher than SHI and SB for the remaining three categories. ICC showed mixed results among reader evaluation for delineation of plaque. However, quantitatively, SHI produced the best vessel-plaque CTR.

Low levels of high-density lipoproteins cholesterol are independently associated with acute coronary heart disease in patients hospitalized for chest pain

INTRODUCTION AND OBJECTIVES

The role of high-density lipoproteins in the context of acute chest pain has not been well characterized. The objective of this study was to determine the relative contribution of lipid profile to the risk of acute coronary syndrome in patients admitted to a cardiology ward for chest pain.

METHODS

We included all consecutive admissions in a single cardiology department over a period of 10 months and 1-year follow-up was performed.

RESULTS

In total, 959 patients were included: 457 (47.7%) were diagnosed with non-ischemic chest pain, 355 (37%) with non-ST-elevation acute coronary syndrome, and 147 (15.3%) with ST-elevation acute coronary syndrome. Prevalence of high-density lipoproteins <40 mg/dL was 54.6%, and was higher in patients with acute coronary syndrome (69.4% vs 30.6%; P<.01). The prevalence of acute coronary syndrome increased with reductions in mean high-density lipoproteins. Age, active smoking, diabetes, fasting glucose >100 mg/dL, and high-density lipoproteins <40 mg/dL were independently associated with acute coronary syndrome, and low high-density lipoproteins was the main associated factor (odds ratio, 4.11; 95% confidence interval, 2.87-5.96). Survival analysis determined that, compared with non-ischemic chest pain, the presence of acute coronary syndrome was associated with significantly greater risk of all-cause and cardiovascular mortality.

CONCLUSIONS

Low levels of high-density lipoproteins cholesterol (≤40 mg/dL) were independently associated with a diagnosis of acute coronary syndrome in patients hospitalized for chest pain, with an inverse relationship between lower levels of high-density lipoproteins and prevalence of acute coronary syndrome.